Ophthalmic illuminators allow a surgeon to illuminate the interior structure of the eye such as the vitreous and the retina during surgical procedures. For example, an endoscopic ophthalmic illuminator (endo-illuminator) includes an optical fiber within the bore of a cannula. By driving a proximal end of the optical fiber with a suitable light source, light emitted from a distal end of the fiber illuminates the desired portion of the eye during a surgical procedure. Alternatively, a physician may illuminate the eye with fiber optic illumination while using an ophthalmic microscope. With the desired portion of the eye sufficiently illuminated, the physician may then perform surgical procedures that may require the use of a vibrating cutting tool such as an ultrasonic handpiece to phaco-emulsify a cataract-clouded lens or an oscillating cutter for vitrectomy procedures. Alternatively, the physician may perform laser photocoagulation therapy to address ocular conditions such as retinal detachments and tears as well as proliferative retinopathy resulting from diseases such as diabetes.
In general, it is desirable to minimize the optical fiber size used during illumination of ophthalmic therapeutic procedures so that corresponding incisions in the eye to admit the fiber can also be made as small as possible. Smaller incisions typically provide better therapy and recovery for the patient. But small fibers will necessarily have smaller etendue. In that regard, the amount of luminous flux or power (lumens) delivered by a fiber equals a product of the source brightness times the fiber etendue. Thus, a desirable decrease in fiber diameter also leads to an undesirable decrease in lumens delivered to the operating field in the eye. One cannot simply increase the number of sources to provide more lumens because of the conservation of etendue principle.
Another issue for ophthalmic illumination is the spectral output. In general, biological tissue is a broadband reflector such that white light illumination is preferable. However, there are situations such as the use of dyes or the detection of certain proteins in which a physician will prefer a suitably colored illumination. In general, most conventional white light sources such as a white light LED provide a fixed spectral output.
Accordingly, there is a need in the art for an improved ophthalmic illuminator that provides sufficient luminous power and also provides an adjustable spectrum.